KR100991415B1 - Method of adjustment for receiver of signals transmitted in bursts and corresponding receivers - Google Patents

Abstract

The present invention relates to a method for adjusting a receiver of a signal transmitted in bursts in a system in which the communication is established in a continuous frame environment comprising slots assignable to the transmitter for communication with the receiver. The adjustment of at least one characteristic of the receiver is adapted to the arrival of the burst by considering at least one reinitialization parameter for the first burst, or an adjustment parameter calculated by the computing unit 4 from the preamble of the currently received burst. Do it.

The at least one prescribed adjustment parameter takes into account the portion of the signal that corresponds to the payload of the previously received burst for this communication if the new burst is separated from this previously received burst only by less than the no-signal threshold. By the computing unit 4 for a new burst of communication.

Description

METHOD OF ADJUSTMENT FOR RECEIVER OF SIGNALS TRANSMITTED IN BURSTS AND CORRESPONDING RECEIVERS}

1 is a block diagram of a receiver manufactured to allow the implementation of the method according to the invention.

FIG. 2 shows scheduled switching times and scheduled adjustments, respectively, when the method forming the subject matter of the present invention is implemented in a receiver, as defined in relation to FIG.

FIG. 3 further shows that means related to frequency adjustment allowing for the implementation of the method according to the invention when the receiver is manufactured to be able to receive pseudo simultaneous bursts from several transmitters in the context of a commonly used time frame. Block diagram of a receiver specifically illustrated.

<Explanation of symbols for the main parts of the drawings>

1: frequency changer 2: input stage

4: operational module 5: input amplifier

7, 16: switch 6, 17: state machine

The present invention relates to a method of coordinating the reception of a signal corresponding to a digital data packet transmitted in a burst in a communication system. This method seeks to dynamically adapt the receiver to the characteristics of the various bursts that are continuously received if at least one communication involves transmissions performed by successive bursts.

The invention also relates to a receiver comprising a device which makes it possible to use this method during the reception of a signal as described above.

Conventionally, well-receiving a signal transmitted wirelessly involves tuning the receiver to the transmission frequency (Ftx) used by the apparatus for transmitting the signal and allowing the receiver to use this frequency (Ftx) under good conditions. It involves gain adjustment to pick up the signal transmitted from the transmitter device. High precision and wide dynamic power ranges for frequency tuning are typically required at the receiver level. This is especially the case when the receiver receives signals related to different applications, which are transmitted within the environment of a wireless communication system where the common standards are fixed and these standards are not necessarily the same. Such hardware may exhibit different characteristics, in particular with respect to power, and may not be under the same conditions with regard to transmission and reception to each other.

It may be difficult to achieve good coordination of the receiver, especially if the received signal corresponds to a digital data packet transmitted in bursts from one or possibly more transmitters. In a system where signals are transmitted in bursts, when the transmitter transmits information to the receiver in bursts, the receiver must be able to quickly lock to the frequency used at the transmitter. In addition, such a receiver must be able to quickly pick up any intended burst correctly by adjusting itself with respect to power so that it is under conditions to recover the data packets making up the payload transmitted by the burst. This is especially a requirement for an OFDM type receiver of a communication system implementing digital modulation, whereby the signal to be transmitted is split over several narrowband channels with different frequencies.

Each receiver must be able to identify, in particular, without the arrival of a burst and thus the failure of the preamble appearing at the head of the burst. Therefore, it should be able to quickly tune itself to the frequency Ftx used to transmit the burst of the packet and / or tailor its gain as a function of the power of the receiving signal.

Conventionally, radio signals picked up by a receiver are considered by subassembly of analog means designed to allow the extraction of radio signals, which are used for the transmission of data packets destined for the receiver, Received by the receiver in the environment.

The subassembly components of the aforementioned means generally comprise an adjustable frequency changer acting by downconversion and an automatic gain controller. The modulator is driven by a signal of frequency Frx and is used to lower the frequency Ftx of the received radio signal. The automatic gain controller comprises an adjustable gain amplifier located downstream of the changer and whose gain is controlled by an adjustment signal G. Such a subassembly is designed to supply a transposed signal, wherein the frequency of the cross signal is in a frequency range allowable by a first stage of the subsequent signal processing subassembly, and the power of the signal is such a first one. Matched to the power allowed at the input by the stage.

By convention, the means of the first subassembly part are pre-adjustable to be effective when a burst is received that may contain useful data.

Therefore, in the case of a burst based communication system, it should be possible to reinitialize the means of the first subassembly component as needed for each new burst.

By convention, the receiver is supplied with two fixed reinitialization parameters, one corresponding to the predetermined value Frst of the frequency correction and the other corresponding to the predetermined value Grst of the gain correction. These parameters are each intended to be used such that one acts on the gain adjustment amplifier and the other acts on the frequency changer.

When a preamble of a new burst is received, it is processed at the level of the receiver receiving the preamble. The purpose of the processing of these preambles is to enable a quick determination of the signal frequency and power associated with the bursts involved and to define the corresponding adjustment parameters. These parameters are used to allow for immediate action on the changer and / or adjustment amplifier when there is a requirement for allowing optimal reception of the packets that make up the payload transmitted by the burst. When the burst is all received, the changer and the adjuster amplifier are usually reinitialized.

However, frequency and power determinations made by considering burst preambles may prove to be inadequate and cause inadequate fine tuning. It is possible that inaccurate and frequent adjustments and / or gain adjustments can result in significant degradation in the receiver's reception performance. It is also possible that a string of transmitted bursts may not be processed by the receiver if the preamble detection step is not performed in a satisfactory manner by such an incorrectly tuned receiver.

Therefore, the present invention is directed to adjusting the receiver to a signal corresponding to a digital data packet transmitted in bursts in a system in which the communication is established within a continuous frame environment that includes a slot assignable to the transmitter for communication with the receiver. Suggest a method. The method allows the receiver to adapt to the arrival of the burst by considering at least one reinitialization parameter determined for the first burst when the burst is currently received, or at least one adjustment parameter computed from the preamble of the burst. Provides adjustment of at least one property of

According to the nature of the method according to the invention, the invention provides a supplemental coordination of the receiver when at least one communication involves a transmission performed by a continuous burst from the transmitter, which complementary coordination, If the new burst is separated from this previously received burst only by a time less than a defined silence threshold, the new burst of communication corresponds to the payload of the previously received burst for this communication. By considering the part of the signal, it is performed by at least one adjustment parameter determined by the operation.

According to the invention, for a new burst of communication by taking into account the part of the signal corresponding to the payload of the previously received burst for this same communication, the adjustment parameter determined by the operation is received based on said part considered. Frequency adjustment parameter corresponding to a frequency drift determined at the receiver's level for the given signal.

According to the invention, for a new burst of communication, the adjustment parameter determined by the calculation by considering the portion of the signal corresponding to the payload of the previously received burst for this same communication is a parameter for adjusting the gain on reception.

In accordance with the nature of the variant of the invention, different defined no-signal thresholds are provided which are optionally associated with various parameter types computed based on the payload of the burst and / or the portion corresponding to the provided application.

The invention also proposes a receiver in which a device is installed which makes use of the method, as defined above.

One such receiver is received as a function of the adjustable means of the low frequency crossover of the received radio signal and of the requirements for the input stage of the subassembly of the data processing means which makes it possible to recover the transmitted data into an available form. Adjustable means of gain control at the input that allows to change the power of the received signal, some parameters based on at least one memory unit for receiver reinitialization purposes, and other parameters by the burst preamble based arithmetic module And means for supplying frequency correction and / or gain correction parameters, the selection of one or more stored or computed parameters, the management of associating state machines with a time base via a switch. Achieved under control of the means, the switch selects parameters as auxiliary means And transmit to the frequency crossing means and the gain adjusting means.

In accordance with the nature of the present invention, such a receiver can also act on the frequency crossover and / or gain adjustment means via frequency switch and / or gain correction parameters via a switch under the control of management means via a burst payload based calculation module. Means for supplying an auxiliary means to be provided.

According to the characteristics of the modified receiver according to the invention, the modified receiver is connected via memory means to a number of switches which are equal to the number of transmitters with which the receiver can communicate at the same time, so that the correction parameters calculated with each burst for each communication. Frequency crossover and / or gain adjustment means by means of which a burst payload based arithmetic module and a selective switch of at least one reinitialization parameter memory unit and another switch with auxiliary means under control of the management means It includes an additional switch that can act on.

The features and advantages of the invention are defined in the following description in connection with the drawings mentioned hereinafter.

According to the invention, the adjustment means are more particularly intended to be implemented in the context of a receiver intended to receive a radio signal corresponding to a data packet transmitted in bursts. As mentioned above, the signal will be a signal undergoing OFDM type modulation.

An exemplary receiver allowing the use of the method according to the invention is shown in FIG. 1. The receiver is adapted to pick up and condition the radio signal in such a way that the radio signal is taken into account, in particular by a signal processing subassembly responsible for extracting useful data that allows such radio signal to transmit. Subassembly parts of the intended analog means.

Conventionally, the subassembly component of the analog means comprises an antenna connected to the frequency changer 1, wherein the frequency Ftx of the signal received by the frequency changer is the first stage 2 of the signal processing subassembly component. Intersected at a reduced level to be taken into account. This first stage 2 is generally an Inverse Fast Fourier Transform (IFFT) computational module, especially in the case of an OFDM receiver.

The modulator 1 is adjustable in such a way that the receiver comprising the modulator can be precisely locked to the frequency Ftx of the signal and then received for optimal reception. In a known manner, this adjustment may be performed by considering adjustment parameters that are predetermined or alternatively calculated from the burst preamble for each new vertex. Usually the predetermined adjustment parameter is a fixed value when there is no burst and more specifically a reinitialization parameter used after the no signal step. The parameter is considered to be stored in the memory unit with reference numeral 3 in FIG. 1.

Upon receipt of this preamble it is possible to determine a new frequency adjustment parameter fpr from the preamble of each new burst. This parameter fpr is here considered to be determined in a manner known to the person skilled in the art by the preamble based computing module 4 of the processed subassembly part. The arithmetic module 4 receives a signal from the changer 1 via an amplifier 5 designed to allow adjustment of the power level of the transmitted signal, which signal is a module of the processing subassembly, ie here a module. It can be used by (2 and 4).

The selection between the parameters frst and fpr is a state of controlling the switch 7 allowing a selective connection to the generator 8 with the unit 3 storing the parameter frst or the preamble based arithmetic module 4. By machine 6. The generator 8 is manufactured in a known manner so as to generate a frequency control signal Frx for the changer 1 as a function of the frequency adjustment parameter it receives.

According to the invention, the state machine 6 and the switch 7 are modified to allow for taking into account the additional frequency adjustment parameter faco calculated by the payload based calculation module 9.

This module 9 is designed to consider the portion of the burst corresponding to the payload and to determine the frequency of the received signal used for this burst in an accurate and known manner to those skilled in the art. The time required for transmission of the payload included in the burst is generally significantly longer than the time required for transmission of the preamble, thus allowing better performance with respect to frequency determination and computation.

In the exemplary embodiment of the receiver shown in FIG. 1, the values considered by the payload based computation module 9 are downstream of the IFFT computation module constituting the first stage 2 of the signal processing assembly component. Supplied by an equalizer 10 located. In the known manner illustrated in FIG. 1, this equalizer 10 is located upstream of the demodulator 11 and decoder 12 arranged in series.

The equalizer 10 is more specifically intended to remove distortion of the received signal due to the channel used for wireless transmission. The demodulator 11 is used to retrieve the coded sequence appearing in the signal from the equalizer, while the decoder 12 uses the sequence supplied by the demodulator to initially plot the data at the level of the output stage 13 of the receiver. To be saved.

Moreover, the equalizer 10 can observe the cycle of equalization coefficients during this burst so that it can determine the ideal frequency Frx to be used to perform the necessary downconversion as a function of the frequency Ftx used for the burst of the received radio signal. do.

According to the invention, the module 9 is used to formulate a frequency adjustment parameter faco taking into account the frequency determined from the part corresponding to the payload of the burst. The switch 7 can be controlled by the state machine 6 to selectively connect either the memory unit 3 or one of the arithmetic modules 4 and 9 to the generator 8. The state machine 6 allows the switching of the input of the switch 7 on the output, which in turn allows for selective connection with the generator 8 as a time counting function. This optional connection is performed in a manner originally known by management logic 18 that includes a time base.                     

The method of operation of the state machine 6 is a no-signal in which the frequency adjustment parameter faco determined from the portion corresponding to the payload of the burst received from the transmitter in the environment of the communication separates these two bursts. Temporarily configured in such a way that it can be used for the next burst of such communication from less than a threshold.

From the moment when a time longer than the no-signal threshold has elapsed from the reception of a burst for constant communication, the receiver described above is returned in accordance with the invention so that the selected frequency adjustment parameter is returned to the usual operating method, which is initially a reinitialization parameter (first). The state machine 6 is provided.

Moreover, in accordance with the present invention, the adjustment method is characterized by the addition of a burst corresponding to this payload, in addition to the parameter Gpr for gain adjustment as a function of the conventionally intended parameter Grst and burst preamble for re-initialization of gain adjustment. The operation performed based on the part gives the possibility to determine the additional gain adjustment parameter Gaco determined by the payload calculation module 9.

Therefore, as described in connection with FIG. 1, in the case of a receiver, these three parameters selectively act on the gain adjustment input that the receiver's input amplifier 5 conventionally comprises via the interface stage 14. To be done. The value of the gain parameter Gaco is obtained by calculation of the ideal gain determined from the average value of the magnitudes of the equalization coefficients observed at the level of the equalizer 10. The value of the gain adjustment parameter Grst at the time of reinitialization and the value of the gain parameter Gpr established as a function of the burst preamble are each supplied in a known manner, where the value of one parameter is here a memory whose reference number is 15. It is supplied from the unit, and the other is supplied from the preamble based calculation module 4.

The switch 16, similar to the switch 7, switches the state machine 17 in such a way that it can selectively connect either the memory unit 15 or the arithmetic modules 4 and 9 with the input of the interface stage 14. Is controlled by means of which the gain of the amplifier 5 is controlled. The state machine 17 is organized such that it can temporarily operate under conditions corresponding to all of the conditions defined above for the state machine 6. The frequency adjustment parameter Gaco, determined from the portion corresponding to the payload of the received burst, is used for the next burst related to the same communication from the moment when the time less than the prescribed threshold separates the two bursts. This threshold may correspond to the threshold intended for the operation of the state machine 6 when the two machines 6 and 17 are used simultaneously, and also when the gain adjustment and the frequency adjustment are performed in parallel. Alternatively, the threshold may be chosen differently so long as power fluctuations due to external disturbances can affect the received signal without affecting the frequency. Of course, if one of the two adjustments proves unnecessary in view of the conditions of use encountered, it may be conceivable to install the receiver for only one of these two adjustments.

As described above with respect to FIG. 1, at the beginning of communication for a given receiver, the gain correction parameter (Grst) value and the value of the first intended frequency correction parameter for reinitialization purposes are used, in particular as shown in FIG. 2. This results in gain correction vs. time with reference number SG0 in the chart. This correction is applied to the signal received before the reception of the first burst, ie burst 1, as shown in the figure. When such a first burst becomes possible to be considered by the preamble-based arithmetic block 4, the block 4 is at the gain of reference SG1 in the chart of FIG. 2 and at the adjusted frequency at reference reference frapb1. Pass the new gain adjustment value (Gpr) and the new frequency adjustment value (fpr) that are used to steer the selection for each. When the portion corresponding to the payload of the burst 1 becomes recoverable by the calculating unit 9, the calculating unit 9 delivers the gain adjusting value Gaco and the frequency adjusting value faco. These two values are then used to steer the selection for gain with reference number SG21 and adjustment frequency with reference number frxaco1 in FIG. 2 when burst 1 ends for the corresponding burst, respectively. These gains and frequencies may remain as possibly as possible with the frequencies and gains previously obtained for the same communication. The next burst of the same communication is here a reference number 2 and if this burst is separated from burst 1 only by a time span with a duration less than a fixed threshold as described above, frxaco1) and received by the receiver representing the gain SG21. Otherwise, the receiver first uses the gain correction parameter (Grst) and the frequency correction parameter (first) in successive reinitialization, and obtains the gain (Gaco) and frequency adjustment value (faco) that can be obtained from the preamble of burst 2. To repeat the operation. The new adjustment value frxaco2 and the new gain value SG22 are obtained again at the end of burst two. The new value of course corresponds to the adjustment value frxaco1 and the gain value SG21. This new value is used if the reception time lag for the next burst 3 is less than the threshold. In this case, as shown in FIG. 2, burst 3 is received by a receiver representing gain SG22 and implementing an adjustment frequency frxaco2, both of which are limited based on the payload transmitted by burst 2. do.

3 is intended to be able to receive a continuous burst corresponding to a data stream in connection with a communication established at the same time, or through this, in the case of the same consecutive frame, for example a different transmitter For the corresponding application, a modified receiver is produced which allows the use of the method according to the invention.

Such a receiver comprises an assembly of an analog means and a signal processing assembly of which is functionally configured in the same manner as the receiver shown in FIG. 1, the module of which comprises a frequency changer 1 ′ of FIG. Reference numerals are numbered in corresponding ways, such as frequency changers. Therefore, the function of the IFFT calculation module constituting the first stage 2 'of the signal processing assembly component in FIG. 3 corresponds fully to the function of the module constituting the first stage of the signal processing assembly component in FIG. It is considered to be. The same is true with respect to the modules 4, 9, 5, 8, 10, 11, 12, 13, 18 of FIG. 1, the preamble based arithmetic module 4 ′ and payload module 9 ′ of FIG. 3. Applied to input amplifier 5 ', generator 8', equalizer 10 ', demodulator 11', decoder 12 ', output stage 13', and management logic 18 '. It is considered to be.

Devices that can intervene at a gain level are not deployed here as long as they can be simply inferred from devices that can intervene on frequency, but are then developed and deployed above in relation to FIG. 1 from the device associated with the gain. .                     

In the example embodiment shown in FIG. 3, the receiver is capable of quasi-simultaneous reception of three different transmissions distributed in different slots in the case of successive frames in which three different transmissions are established. It is considered to be intended to allow. Such a transmission may be performed at a different frequency (Ftx) and relatively different power, especially if the transmission is considered to come from a different transmitter.

Two cases are intended here, one case where the receiver knows the transmission order of the transmitters, so that one can define what will be the next active transmitter that should receive the burst at a given moment, and the other Is the case when the receiver does not recognize what the next active transmitter will be. The first case relates in particular to the downlink, uplink, and direct link communication systems of the Hyperlan 2 network. The second case is for links organized according to the 802.11a standard, for example.

In both cases, when there is no communication, an initially predetermined frequency correction parameter frsti is prepared for the receiver stored in the memory unit 3'i for reinitialization. In addition, different parameters are prepared for each of three specific communications that can be established at the same time, wherein each of these predetermined parameters frst1, frst2, frst3 are here different memory units 3'1, 3'2, 3'3. Is considered to be stored in. Moreover, it is intended that the preamble based computing unit can supply the adjustment parameter fpr upon reception of each burst preamble as before. These parameters are sent to the inputs of the switches 7'1, 7'2, 7'3 assigned to the communication in which the received burst forms part. According to the invention, the payload based computing unit 9 'can supply a frequency adjustment parameter faco from each useful part of the received communication burst. If the burst precedes the burst of the same communication within a time lag less than the defined no-signal threshold, it is ready to use the parameter faco obtained for the first burst to adjust the frequency Frx of the receiver for a second reception. do. The no signal threshold will not be chosen to be as identical as possible for all communications. The adjustment parameters faco1, faco2 and faco3 respectively obtained are temporarily held in elements 19'1, 19'2 and 19'3 of the memory supplied by the payload based computing unit 9 '. Each element 19'1, 19'2, or 19'3 temporarily stores a storage parameter computed for the last received burst of the allocated communication, thereby selectively switching switches 7'1, 7 Allow transmission to the control input of the generator 8 'via' 2 or 7'3).

As before, the state machine 6'1, 6'2 or 6'3 is associated with each switch 7'1, 7'2, 7'3. The additional switch 7's to which the additional state machine 6's is assigned is the output of the memory unit 3'i, or the switches 7'1, 7 under the control of the management logic 18 'acted by the various state machines. Used to selectively connect the output of either '2, 7'3) to the control input of the generator 8'. Then, the operation is performed in a manner similar to that described above with respect to the receiver shown in FIG. Parameters related to communication, for example frst1, Fpr1 and faco1, are optionally used here under conditions similar to those described above in the case of defined communication which is first considered to be established via the first transmitter. The same applies for the parameters frst2, Fpr2 and faco2 in connection with the second communication established via the second transmitter, for example, the parameter frsti being used in case of complete reinitialization.

As described above, the present invention relates to a method of coordinating the reception of a signal corresponding to a digital data packet transmitted in bursts in a communication system, in which case at least one communication involves transmission performed by successive bursts. Effective for dynamically adapting the receiver to the characteristics of the various bursts that are continuously received, and also for a receiver or the like comprising a device which makes it possible to use this method during the reception of a signal as described above.

Claims (6)

Coordinating the receiver of a signal corresponding to a digital data packet transmitted in bursts within a system in which communication is established within a continuous frame context that includes a slot assignable to the transmitter for communication with the receiver. The method comprises: considering the at least one reinitialization parameter determined for a first burst or at least one adjustment parameter calculated from a preamble of the burst when a burst is currently received, the receiver causes the burst A method of adjusting a signal receiver, the method of providing adjustment of at least one characteristic of the receiver to adapt upon arrival of In the case where at least one communication involves transmission performed by a continuous burst from the transmitter, it provides complementary coordination of the receiver, the supplemental coordination, the silence of which a new burst is defined. If it is separated from this previously received burst only by less than a threshold time, the operation is considered by considering the portion of the signal corresponding to the payload of the burst previously received for this communication for a new burst of communication. Characterized in that it is performed by at least one adjustment parameter determined by. The adjustment parameter determined by the calculation according to claim 1, wherein the adjustment parameter determined by the calculation is based on the considered part by considering a portion of the signal corresponding to the payload of the burst previously received for this same communication for a new burst of communication. And a frequency adjustment parameter corresponding to a frequency drift determined at the level of the receiver with respect to the received signal. 3. The adjustment parameter of claim 1 or 2, wherein the adjustment parameter determined by the operation is determined by taking into account the portion of the signal corresponding to the payload of the previously received burst for this same communication for a new burst of communication. It is a parameter for adjusting the, characterized in that for adjusting the signal receiver. 3. A method according to claim 1 or 2, wherein differently defined no-signal thresholds are provided which are optionally associated with various parameter types calculated based on the portion corresponding to the payload of the burst. A receiver of a signal corresponding to a digital data packet transmitted in bursts in a system in which communication is established within a continuous frame environment comprising slots assignable to the transmitter for communication with the receiver, Adjustable low frequency transposition means 1 of the received wireless signal, Adjustable gain at the input that can transform the power of the received signal as a function of the requirements of the input stage 2 of the subassembly of the data processing means to allow the transmitted data to be recovered in a usable form. Control means 5, Some are based on at least one memory unit 3, 15 for receiver reinitialization, and others via burst preamble based arithmetic module 4 to provide means for supplying frequency correction and / or gain correction parameters. Include, The selection of one or more stored or calculated parameters is accomplished under the control of management means for associating a time base with the state machine 6, 17 via switches 7, 16, and the switches 7, 16. ) Selectively transmits the parameter to the auxiliary means (8, 14), allowing it to act on the frequency crossing means and the gain adjusting means, In the receiver of the signal, Characterized in that it further comprises means for supplying a frequency correction and / or gain correction parameter to said auxiliary means via said switch under the control of said management means via a burst payload based calculation module 9, Receiver of the signal. 6. The burst payload based computing module (9 ') according to claim 5, characterized in that the memory is stored in a plurality of switches (7'1, 7'2, 7'3) equal to the number of transmitters with which the receiver can communicate simultaneously. Connected via means 19'1, 19'2, 19'3, it is possible to store calibration parameters computed in each burst for each communication, and further switches, under the control of said management means, with other switches. A receiver of the signal, allowing selective connection with at least one re-initialization parameter memory unit (3'i) to act on said frequency crossing means and / or gain adjusting means.

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